Cloud
Cloud names 3 different subjects across the 6 encyclopedias on this shelf. Each is set out below.
Cloud a mass of small globules of water
Aiton's Encyclopedia (1910)
a mass of small globules of water, or of ice and snow, suspended in the air. Clouds are formed by the evaporation of water from land and sea. There is a theory that the condensation of the water vapor, which is so fine as to be invisible, into the larger globules of visible clouds, is due not only to a cooling of the air, but, in part at least, to the presence of dust particles and the repelling and attracting influence of electricity. Scientists have found that pure, dry air may be laden with vapor and be cooled without condensation but that, if at this point in the experiment, dust be injected without a change of temperature or the addition of more vapor, a mist forms at once. Clouds form and float at widely different heights. It is not difficult, especially when a storm is coming up, to note clouds at different altitudes moving in two or more entirely different and even opposite directions, showing that they are floating in different layers of air. The warmer the air, the more moisture it can carry. When air has all the moisture it can carry it is said to be saturated. If saturated air be warmed it can take up more moisture. If saturated air be cooled it must drop part of its moisture, and we have a shower, or a rain, or a dew. Clouds are not merely of great benefit, but are indispensable in carrying moisture from the place of their formation to the places where moisture is needed, and where shade is welcome. Shelley expresses this thought beautifully in his Cloud: I bring fresh showers for the thirsting flowers From the seas and the streams; I bear light shade for the leaves when laid In their noon day dreams. From my wings are shaken the dews that waken The sweet buds, every one When rocked to rest on their mother's breast, As she dances about the sun. Clouds are classified according to their form and height. The chief three kinds are: 1. The cirrus, a light, feathery cloud frequently seen streaming across the sky. Cirrus clouds move swiftly, and are high up, six to ten miles, in a wind-swept region. 2. The cumulus or fleecy cloud is piled up like a fleece of wool. The bases of cumulus clouds are flat and the upper parts are dome-shaped. They pile up and tumble about as if tossed by strong winds and take innumerable forms of mountains, castles, minarets, and towers. 3. The nimbus, a dark, low, rain cloud. Rents in a nimbus frequently give magnificent views of the upper regions and other clouds. It would be a mistake to suppose that all clouds can be referred to these three forms; for clouds occur in all sorts of combinations and intermediate forms, delightful to study. A cloud record is kept readily by a numerical scale of from 1 to 8. An entry of 0 indicates a clear sky; 8 a dark, clouded sky in which no blue can be seen, and in which the sun cannot be located. The brilliant colors of the clouds, gray, purple, orange, yellow, olive, and pink, are due probably to the refraction of light by minute dust particles rather than to the globules of water. The height of clouds is found by two observers located at two ends of a given base line . Each observer measures the angle formed between the base and a line directed toward a part of the cloud agreed upon. From the length of the base and the value of the two angles adjacent to the base, the altitude of the triangle, that is to say, the height of the cloud, is easily computed. See Dew ; Frost; Hail ; Rain
Cloud ST. cloud of loose or fibrous structure
Collier's New Encyclopedia (1921)
ST. cloud of loose or fibrous structure, feathery in appearance and of great variety-said to have been seen at an altitude of 10 miles. Its particles are supposed to be frozen and crystallized, which give rise to halos, coronæ, and other optical appearances. Cirrus is said to be often the precursor of windy weather or changes. Their movement is generally different from that of the lower clouds. Cumulo-stratus-A modification of cumulus; flat-topped, mushroom-shaped masses; have a tendency to spread and overcast the sky, and indicate coming rainy weather. Cirro-stratus-A fibrous cirrus cloud in close horizontal arrangement. Sky mottled with these clouds is known as mackerel sky. Often precedes wind and rain. Cirro-cumulus-Small, round masses, disposed with more or less regularity; usually a high level cloud, though below that of cirrus. They appear most frequently in dry and warm weather. Nimbus-A low cloud, from which rain is falling, the masses so blended together as to form no definite outline. Scud-A term referring to low, detached clouds, drifting rapidly before the wind. Precipitation, or rain, is one of the most irregular of all meteorological phenomena, there being places of habitual dryness throughout the year with but occasional sprinklings. Tropical countries generally have a dry and a wet season, and there are other localities where rain may fall irregularly at all seasons. There are places where the annual rain-fall amounts to several hundred inches. Fifty inches per annum may be regarded as a moderate rain-fall, and below 20 inches a very light one, and generally insufficient for agricultural purposes unless it should fall in the right season. The study of clouds and their movements has, in recent years, been greatly extended through international agreements and co-operation. The development of aeronautics has greatly advanced our knowledge regarding clouds and, on the other hand, has made more accurate and extensive knowledge regarding them a matter of practical necessity rather than theoretical interest.
Cloud ST., a town of France
Collier's New Encyclopedia (1921)
ST., a town of France, in the department of Seine-et-Oise, a few miles from and S. W. of Paris. The historical associations of this place are intimately connected with the royalty of France. Its palace, which is very beautiful, was originally the property of the Dukes of Orleans, and, for a long period, was a summer residence of the kings of France. Its fountains are extremely elegant, and its park extensive. Here, in 1799, Napoleon I. dismissed the Assembly of Five Hundred, and caused himself to be proclaimed first consul; and here, in 1830, Charles X. put his signature to the ordinances which cost him his throne.
What Has Changed in the Last Century
The dust-and-condensation theory Aiton's called "a theory" in 1910 is settled science: cloud droplets form on aerosol condensation nuclei, and the coloured tints the entry attributed to "refraction of light by minute dust particles" are now explained as scattering by the water droplets themselves. The three-and-then-some scheme of the old entries has been formalised by the World Meteorological Organization into ten genera; nimbus, the "dark, low, rain cloud" both accounts lean on, was dropped as a genus in 1956 in favour of nimbostratus and cumulonimbus, and the Atlas gained new terms including the roll cloud volutus and the wave-like asperitas in 2017. Cloud height is no longer computed from two observers and a base line but read off ceilometers, weather radar, radiosondes and satellites, beginning with TIROS-1 in 1960 — while the 0-to-8 scale for sky cover survives as the okta. Collier's other Cloud, the town of St. Cloud, is no longer in Seine-et-Oise: that department was abolished in 1968 and the town now sits in Hauts-de-Seine.
Written for this edition, 2026.